External pipe cleaning machines have been utilized in the pipeline industry for years. The outside surfaces of the pipes are cleaned before application of primer, tape or other protective coatings. Proper surface preparation of the pipe is thus an important step in pipeline construction.
Since pipelines can be of various sizes, it is desirable for pipe cleaning machines to accommodate pipes of different diameters. To this end there have been several approaches to the design of the cleaning head assemblies in such machines. One approach has been to mount the cleaning elements on pivotal arms which are biased inwardly by springs. Although more than one pipe size can be accommodated this way, engagement between the brushes and the pipe varies in accordance with the pipe size. The brushes are engaged with greater tension against larger pipes. Brush engagement with smaller pipes can be inadequate to properly clean the outside pipe surface. The angle of brush contact in assemblies of this type can also vary in accordance with the pipe diameter. Such self-adjusting assemblies are thus effective only for a relatively narrow range of pipe sizes.
Another approach has been to mount the brushes in fixed relationship. More uniform engagement and contact between the brushes and the pipe surface is achieved in this manner, but ease of adjustment is difficult. To effect a changeover in pipe size, it has heretofore been necessary to change several components in the mechanism. This in turn has required substantial disassembly and then reassembly of the mechanism, all of which is time consuming and therefore expensive in terms of labor. There is thus a need for an improved quick-change brush head for use in a pipe cleaning machine.